Means for controlling illumination of control or service elements on motor vehicle

ABSTRACT

A light guide for illuminating display elements in a vehicle, which elements are on the dashboard, or the like; the guide comprises a light source, and a light guide positioned over both the elements to be illuminated and the light source; the light guide has an exterior surface which is spaced away from the elements being illuminated and which curves gradually toward the surface to be illuminated along the direction away from the light source thereby to concentrate light in the light guide body remote from the source; in certain embodiments, a prismatically shaped light guiding body intersects the principal light guide for concentrating light at a particular display element.

United States Patent 1191 1 Feb. 12, 1974 I [22] Filed:

[541 MEANS FOR CONTROLLING ILLUMINATION OF CONTROL OR SERVICE ELEMENTSON MOTOR VEHICLE [75] Inventor: Giinter Dietz,Wuppertal-Barmen,

, Germany [73] Assignee: GEBR Happich GmbH,

Wuppertal-Elberfeld, Germany Aug. 1, 1972 [21] Appl. No.: 276,903

[30] Foreign Application Priority Data 3/1967 Hardesty 240/8.16 x3,150,456 9 1964 Roper 240/8.16 x 3,029,334 4/1962 Anderson et al. 240/1EL 2,761,056 8/1956 Lazo 240 1 EL x 3,561,145 2/1971 Shotwell 240/1 EL xPrimary Examiner-Samuel S. Matthews Assistant Examiner-Richard A.Wintercor'n Attorney, Agent, or Firm-Ostrolenk, Faber, Gerb & Soffen[57] ABSTRACT A light guide for illuminating display elements in avehicle, which elements are on the dashboard, or the like, the guidecomprises a light source, and a light guide positioned over both theelements to be illuminated and the light source; the light guide has anexterior surface which is spaced away from the elements ,beingilluminated and which curves gradually toward the surface to beilluminated along the direction away from the light'source thereby toconcentrate light in the light guide body remote from the source; incertain embodiments, a prismatically shaped light guiding bodyintersects the principal light guide for concentrating light at aparticular display element.

11 Claims, 8 Drawing Figures MEANS FOR CONTROLLING ILLUMINATION OFCONTROL OR SERVICE ELEMENTS ON MOTOR VEHICLE The present inventionrelates to illumination by a remote light source of a display andparticularly to illumination of control or service elements in avehicle, e.g. on the vehicle dashboard. The invention comprises a lightguide structure which transmits light from a cen tral illuminationsource to the display and then enables the display to be uniformlyilluminated.

Various light guide structures are known for illuminating displays,particularly wide displays which may include longitudinally disposedsymbols. A light guide structure is capable of transmitting lightthrough its interior. It is bounded by exterior surfaces, the interiorsides of which reflect light when the angle of incidence of the light onthe interior sides is greater than a critical angle, and permit light topass through, when the angle of incidence is less than the criticalangle. Since light from a central source is emitted in many directions,it is incident on the interior sides at various angles. Hence, lightexits from the guide structure along its entire length.

Conventional light guide structures have bodies of uniform thicknessover their entire length. The bodies may include openings through whichcontrol buttons and levers may pass. These conventional structures havethe disadvantage that they do not adequately transmit the light and toomuch of the light' is emitted near the source, whereby illumination froma central source rapidly decreases in intensity away from the source.This provides non-uniform illumination across the display andinsufficient illumination of some of the remote sections ofthe display.

To overcome this drawback, the prior art'provides a strong light sourceto illuminate the remote display sections. However, a strong lightsource may be disturbing, particularly when the display is being used indarkness, e.g., when the display is on the dashboard of a vehicletraveling along a darkened road. If the light source is adapted to thedarkened conditions, the furthest display elements are not sufficientlyilluminated. The difficulties in illuminating a display are increasedwhen the illumination is indirect or when the light must pass throughopenings, particularly long slits, which greatly reduces the lighttransmitting ability of these light guide structures.

The present invention provides more uniform and adequate illumination ofeven remote sections of a display than the prior art. A light guidestructure in accordance with the invention is shaped so that itcontinuously decreases in its cross-section in a direction that is bothtransverse to the direction in which light is transmitted through thelight guide structure and is away from the light source toward the moreremote sections of the display to be illuminated. Preferably, thedecrease in cross section is nonlinear and gradually sloping away fromthe light source.

It is advantageous to provide the continuously reduced cross-section forthe light guide structure by making at least one, and perhaps more thanone, of the reflective interior sides of the exterior surfacesspheroidally concavely curved along the portion of the light guide awayfrom the source of illumination toward the more remote sections of thedisplay to be illuminated. The curved surfaces would usually comprise atleast the surface opposite the surface of the display and mightadditionally comprise the surface adjacent to the display.

Usually, the light source is intermediate the ends of the light guidestructure and the structure has decreasing cross-section extending awayin opposite directions to the opposite ends of the structure. However,the light source need be spaced away from only one end of the structureand it is the portion of the structure between the light source and thatone end that is of diminishing cross section.

In the preferred embodiment of the invention, the light guide structurenot only reduces in cross-sectional area moving away from the lightsource, it gradually also changes its shape. For example, a light guidestructure may start near the light source with a rectangularcross-section and its surface might gradually curve so that thestructure develops a cross-section which is prismatic in shape, havingthree interior sides defined by three exterior surfaces. With such anarrangement of the light guide structure, light is selectively guidedfor reflection along one or the other of the interior sides of theexterior surfaces.

Light from the central source is: transmitted through the light guidestructure. The light strikes the interior sides of the exterior surfacesof the light guide and some of the light is reflected along the lightguide structure. Light striking the interior sides of the exteriorsurfaces of the light guide is reflected at an angle ofreflection equalto the angle of incidence of the light. Because of the reducingcross-section of the light guide structure, the angles of incidence andreflection of the light also gradually reduce in the direction away fromthe light source, whereby the light density increases with eachreflection. The greater light density remote from the central lightsource of thelight still being transmitted by the guide structureprovides the more remote regions of the display with more intenseillumination thanmight otherwise be expected.

If aspecial region of the display is to be illuminated with greaterintensity than other nearby areas, the light guide may at thatcorresponding position have a prismatic shape, and this prismaticsection would extend transversely to the normal transmission of lightthrough the light guide. The additional prismatically shaped section maycomprise a prism like body which is either placed over or passes throughthe main light guide structure. Only a portion of the light beingtransmitted through the main light guide structure should pass throughthe separate prismatic portion thereof leaving another sufficientportion of the light to be guided further along the light guidestructure to the remote areas of the display requiring illumination.

In another embodiment of the invention, the light guide structureincludes at least one open gap, with a prismatic body section beingpositioned beyond each gap and remote from the light source. Thisarrangement enables illumination along the gap edge surfaces of thelight guide structure.

It is an object of the present invention to provide a light guidestructure which adequately transmits illumination from a central sourceto remote sections of a display being illuminated.

It is another 'object of the invention to provide such a light guidestructure which sufficiently illuminates the remote sections of thedisplay even when they are so far from the light source as to precludetheir being directly illuminated thereby.

It is a further object of the invention to provide such a light guidestructure which uniformly illuminates the entire display.

The foregoing and other objects of the invention will be betterunderstood from the following description of the accompanying drawingsin which:

FIG. 1 is a longitudinal cross-sectional view through an illuminationdevice carrying a light guide structure in accordance with theinvention;

FIG. 2 is a top plan view of the light guide structure shown in FIG. 1;

FIG. 3 is a side view in the direction of arrows 3 in FIG. 2 of thelight guide structure;

FIGS. 4 and 5 are cross-sections of the light guide structure of FIG. 2along the lines and in the direction of arrows 44 and 5-5, respectively;

FIG.'6 is a top perspective view of the light guide structure viewedfrom the same side as the view in FIG.

FIG. 7 is a longitudinal cross-sectional view through another type oflight guide structure in accordance with the invention; and- I FIG. 8 isa top perspective view of the light guide structure of FIG. 7.

FIG. 1 shows an illuminating device which an observer views in direction21. The device includes a light guide structure 1, which is held withinhousing 2 and over which is positioned cover plate 3 that carries on itsface symbols or other indicia which are to be illuminated. Housing 2comprises two frame'members 4, which are joined by a bridge 5. Bridge 5includes suitable supports for receiving two conventional electric lightsources 22. Frame members 4 include front openings 7, which correspondsin position to the openings 8 in light guide structure 1 and whichpermit access to operating knobs, or the like, extending out of theilluminating device.

Light guide structure 1 comprises two ring shaped bodies 9, which areintegrally formed with and joined by central joining bridge 10.Structure 1' is comprised of an appropriately transparent, conventional,light transmitting material, e.g., glass, or a plastic material known bythe trademark Lucite. Ring bodies 9 define flat walled 2'4 openings 8through which the display on cover plate 3 is viewed. The illuminationtransmitted by ring bodies 9 illuminates openings 8 and cover plate 3.

Bridge 10 has interior openings 6, each for receiving an electric lightbulb 22. These bulbs comprise the central source of light for structure1.

In the center of bridge 10, between openings 6, structure 1 is providedwith a V-shaped groove 11, which defines two V-ed surfaces that togetheract as a prism formation at the center of the bridge. Prism formation 11is transverse to the normal direction of light transmission from eachsource 22 across bridge 10 and groove 11. The groove causes more intenseillumination of the portions of the display that are visible throughopenings 8 adjacent to the center of bridge 10'.

Ring shaped bodies 9 of structure 1 are shaped so that the interiorsides 25 of their external surfaces cooperate to reflect light that isincident upon interior sides 25 at an angle greater than a predeterminedcritical angle of incidence. Any light incident on the sides 25 at anangle less than the critical angle passes through the respectiveexternal surface and illuminates the surrounding area.

As shown in FIG. 1, lower surface 12 of structure 1 is flat and ispositioned above cover plate 3 to be illuminated. At bridge 10, lowersurface 12 and upper surface 13 of structure 1 are parallel. Away frombridge 10, upper surface 13 of structure 1 is spheroidally curved orarched, as is apparent from the side view, FIG. 3, and the cross-sectionview, FIG. 4, so that the rectangular cross-section of structure 1 inFIG. 5 merges into a generally triangularly cross-sectioned region 15 inthe direction away from light source openings 6. This inherentlyproduces a surface 25A which gradually twists from the more horizontalorientation generally parallel to surface 13, as shown in FIG. 4, to themore vertical orientation transverse to surface 13, as shown in FIG. 3.As a result, light emanating from openings 6 and moving outwardly towardthe remote end 26 of structure 1 is incident upon downwardlyspheroidally curving interior side 25 of upper surface 13 of guidestructure 1 and upon the interior side of gradually twisting surface25A. The spheroidal concave curvature of this interior side causes eachreflection of light from surface 13 back toward flat lower surface 12 tobe at a smaller angle of incidence upon side 25 of surface 12, asschematically suggested in FIG. 3, and each successive reflected lightray is shorter in length. The shorter and closer light rays toward thenarrower rim region at end 26 of light guide structure 1 causes gradualintensification of the remaining light that has not already passed outof body structure 1 and thereby aids in the emission from ring body 9 oflight of generally uniform intensity further from light source openings6 than would otherwise be possible. Whenever the angle of incidence ofsome of the light on side 25 of surface 12 is less than the criticalangle, the reflected light is emitted through surface 12 to illuminatecover plate 3. This arrangement causes substantially uniformillumination across the length of body structure 1. Furthermore, thismakes it possible to indirectly illuminate the regions remote from lightopenings 6.

In a further situation, not shown, the ring shaped regions 9 may beprovided with a surrounding illuminated surface.

FIGS. 7 and 8 show a modified light guide using the principle of thepresent invention. Light guide body 16 is provided along its edge rimswith prism shaped body sections 17 which are joined to body 16 at theirends by cross-bar support elements 27 and which are separated from body16 along its edge rims by respective slit openings or air gaps 19. Lightguide body 16 and sections 17 are also comprised of one of theaforementioned light transmitting materials. Light is provided by asingle centrally disposed light source 18. The light is transmittedoutwardly through light guide body 16 across gaps 19 to prism shapedbodies 17, which are disposed transversely to the normal transmission oflight through body 16. Light travels into bodies 17 and is directedalong the bodies because of their prismatic shape. The prism shapedbodies 17 do not rely upon surface curvature, as in the embodiment ofFIGS. 1-6, but instead rely upon their prismatic shape to transmit thelight along the length of body 16.

Although the present invention has been described in connection with apreferred embodiment thereof, many variations and modifications will nowbecome apparent to those skilled in the art. It is preferred,

therefore, that the present invention be limited not by the specificdisclosure herein, but only by the appended claims.

I claim:

1. A light guide structure for uniformly illuminating a display below anopening through said structure:

said structure being comprised of a block of light transmittingmaterial; said block having a first and second end and a top and abottom surface; a receptacle for a light source, which said receptacleis disposed away from said first end and is positioned to cause light tobe transmitted through said block toward said first end;

said block being defined in shape by external surfaces having interiorsides facing inwardly into said block; said interior sides of saidexternal surfaces of said block having reflective capability when lightis incident thereupon at less than a critical anan opening passingthrough said block and through said top and bottom surfaces and beinglocated between said light source receptacle and said first end; an endportion of said block surrounding said opening and having a wall facinginto and defining said opening;

said end portion having a generally rectangular crosssection across saidtop and bottom surfaces in the vicinity of said light source receptacleand having its cross-section gradually change shape, moving away fromsaid light source receptacle toward said one end, into a generallytriangular shape, with the apex directed outwardly from said opening;said cross-section of said end portion also gradually decreasing inheight between said top and said bottom surfaces moving away from saidlight source receptacle toward said one end; all of this cross-sectionchange giving said end portion a generally spheroidal shape thatisconcave with respect to said exterior surface interior sides;

the aforesaid changes in said block cross-section causing one saidinterior side of an external surface of said end portion to graduallytwist, moving away from said light source receptacle toward said one endand thus also moving around said opening to cause said one interior sideto cooperate with the other said interior sides to reflect lightgenerally uniformly around said opening moving from said light sourcereceptacle to said first end.

2. The light guide structure of claim 1, wherein said light sourcereceptacle is positioned generally centrally between said first and saidsecond ends and both said ends and the said portions of said structureleading to those said ends having the aforesaid characteristics of thefirst said end and the said end portion leading thereto.

3. The light guide structure of claim 1, wherein it is said top surfaceof said block that changes to change the shape and cross-section of saidend portion.

4. An illuminating device, including the light guide structure of Claim3, and further comprising:

a framework supporting said structure; said framework carrying a displayto be illuminated; said display being positioned across said structureand across said structure opening and adjacent the said bottom surfaceof said structure. 5. The light guide structure of claim I. wherein saidstructure has a prismatically shaped region that extends transversely tothe normal transmission of light through said structure for interceptingthe light and intensifying light in the vincinity of said prismaticallyshaped region.

6. The light quide structure of claim 5, wherein said prismaticallyshaped region comprises a notch in the said structure external surfacethat carries said interior side that is curved.

7. The light guide structure of claim 1, wherein said opening is roundand said end portion is rounded in a manner to encircle said. opening.

8. The light guide structure of claim 7, wherein said block hasperipheral edges which extend into and be come part of said end portion;said light source receptacle being at said peripheral edges, thereby totransmit light straight into said end portion around said opening alongboth said peripheral edges and to said first end.

9. The light guide structure of claim 8, wherein said light sourcereceptacle is positioned generally centrally between said first and saidsecond ends and both said ends and the said portionsof said structureleading to those said ends having the aforesaid characteristics of thefirst said end and the said end portion leading thereto.

10. An illuminating device for carrying illumination to a remotelocation, said device comprising:

a light guide structure having a light transmitting capability and beingsupportable in means for sup porting a light guide structure before adisplay to be illuminated; said structure having a first and second end;a light source disposed away from at least one of said ends andpositioned to transmit light through said structure;

said structure having a prismatically shaped region that extendstransversely to the normal transmission of light through said structurefor intercepting the light and intensifying light in the vincinity ofsaid prismatically shaped region;

said prismatically shaped region extending along the length of saidstructure from said light source to the one said end; said structurehaving a rim away from said light source and said prismatically shapedregion extending along said rim.

11. The illuminating device of claim 10, wherein said prismaticallyshaped region comprises a prismatically shaped body; means supportingsaid prismatically shaped body spaced away from and across an air gapfrom said structure and from said light source.

1. A light guide structure for uniformly illuminating a display below an opening through said structure: said structure being comprised of a block of light transmitting material; said block having a first and second end and a top and a bottom surface; a receptacle for a light source, which said receptacle is disposed away from said first end and is positioned to cause light to be transmitted through said block toward said first end; said block being defined in shape by external surfaces having interior sides facing inwardly into said block; said interior sides of said external surfaces of said block having reflective capability when light is incident thereupon at less than a critical angle; an opening passing through said block and through saId top and bottom surfaces and being located between said light source receptacle and said first end; an end portion of said block surrounding said opening and having a wall facing into and defining said opening; said end portion having a generally rectangular cross-section across said top and bottom surfaces in the vicinity of said light source receptacle and having its cross-section gradually change shape, moving away from said light source receptacle toward said one end, into a generally triangular shape, with the apex directed outwardly from said opening; said crosssection of said end portion also gradually decreasing in height between said top and said bottom surfaces moving away from said light source receptacle toward said one end; all of this crosssection change giving said end portion a generally spheroidal shape that is concave with respect to said exterior surface interior sides; the aforesaid changes in said block cross-section causing one said interior side of an external surface of said end portion to gradually twist, moving away from said light source receptacle toward said one end and thus also moving around said opening to cause said one interior side to cooperate with the other said interior sides to reflect light generally uniformly around said opening moving from said light source receptacle to said first end.
 2. The light guide structure of claim 1, wherein said light source receptacle is positioned generally centrally between said first and said second ends and both said ends and the said portions of said structure leading to those said ends having the aforesaid characteristics of the first said end and the said end portion leading thereto.
 3. The light guide structure of claim 1, wherein it is said top surface of said block that changes to change the shape and cross-section of said end portion.
 4. An illuminating device, including the light guide structure of Claim 3, and further comprising: a framework supporting said structure; said framework carrying a display to be illuminated; said display being positioned across said structure and across said structure opening and adjacent the said bottom surface of said structure.
 5. The light guide structure of claim 1, wherein said structure has a prismatically shaped region that extends transversely to the normal transmission of light through said structure for intercepting the light and intensifying light in the vincinity of said prismatically shaped region.
 6. The light quide structure of claim 5, wherein said prismatically shaped region comprises a notch in the said structure external surface that carries said interior side that is curved.
 7. The light guide structure of claim 1, wherein said opening is round and said end portion is rounded in a manner to encircle said opening.
 8. The light guide structure of claim 7, wherein said block has peripheral edges which extend into and become part of said end portion; said light source receptacle being at said peripheral edges, thereby to transmit light straight into said end portion around said opening along both said peripheral edges and to said first end.
 9. The light guide structure of claim 8, wherein said light source receptacle is positioned generally centrally between said first and said second ends and both said ends and the said portions of said structure leading to those said ends having the aforesaid characteristics of the first said end and the said end portion leading thereto.
 10. An illuminating device for carrying illumination to a remote location, said device comprising: a light guide structure having a light transmitting capability and being supportable in means for supporting a light guide structure before a display to be illuminated; said structure having a first and second end; a light source disposed away from at least one of said ends and positioned to transmit light through said structure; said structure having a prismatically shaped region that extends transversely to the normal transmissioN of light through said structure for intercepting the light and intensifying light in the vincinity of said prismatically shaped region; said prismatically shaped region extending along the length of said structure from said light source to the one said end; said structure having a rim away from said light source and said prismatically shaped region extending along said rim.
 11. The illuminating device of claim 10, wherein said prismatically shaped region comprises a prismatically shaped body; means supporting said prismatically shaped body spaced away from and across an air gap from said structure and from said light source. 